Ratchet wrench with dual pawl members

Details Ratchet wrench with dual pawl members Ratchet wrench with dual pawl members

2000-02-14

2001-03-27

Scherbel, David A. (Department: 3723)

Tools

Wrench, screwdriver, or driver therefor

Handle clutched to head

Reexamination Certificate

active

06205891

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a ratchet wrench having two pawl members separated by an operation member in the head of the wrench and each pawl member is connected with a spring. Each pawl member has two inclined surfaces which alternatively contacts the operation member when the pawl member is engaged with the threaded inner periphery of the head.
BACKGROUND OF THE INVENTION
A conventional ratchet wrench known to applicant was disclosed in U.S. Pat. No. 4,762,033 to Chow; Kirk K., with the title of “Ratchet Wrench With Manual Disassembly Capability”. Chow's wrench employs a single pawl member to engage with a threaded inner periphery of the head of the wrench so as to output an torque when rotating the shank of the wrench. However, the single pawl member obviously can provide only limited numbers of teeth of the pawl member to match with the threaded inner periphery of the head so that the wrench cannot generate a large torque.
Some ratchet wrenches improve the inherent shortcoming and were disclosed in U.S. Pat. No. 3,372,612 to M. T. Rozmus, with the title of “Pawl Type Ratchet Wrench”, U.S. Pat. No. 4,137,801 to Imperio; Charles D., with the title of “Combined Ratchet And Torsion Wrench”, U.S. Pat. No. 5,537,899 to Thomas J. Diedrich, with the title of “Dual-Pawl Ratcheting Mechanism With Provision For Preventing pawl Jamming”, and U.S. Pat. No. 5,782,147 to Peter Constantine Chaconas et. Al., with the title of “Ratchet Wrench Having Two-Pawl Action”.
Although there are two pawl members engaged with the threaded inner periphery of the head, when rotating the wrench, each pawl member is pushed by the operation member in the head by only a point. This could break the corner end of the pawl members when a large torque is applied.
The present invention intends to provide a ratchet tool that provides a sufficient contact surface to each pawl member when the other end of each pawl member is engaged with the threaded inner periphery of the head.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, there is provided a ratchet wrench and comprising a ring-shaped head with a threaded inner periphery and an operation member is rotatably retained in the head. The operation member has a disk portion, an engaging shaft extending from one side of the disk portion and a ridge member extending from the other side of the disk portion. A flange extends from the ridge member so as to define two recesses radially between the disk portion and the flange. The two recesses are separated by the ridge member and two pawl members are respectively received in the two recesses. Each pawl member has a first side with teeth defined therein, a second side of each pawl member comprising two inclined surfaces on two end of the second side and a straight surface connected between the two inclined surfaces. The teeth of each pawl member are engageable with the threaded inner periphery of the head and one of the two inclined surfaces and the straight surface of each pawl member is engaged with respective one of the two parallel surfaces of the ridge member. An operation disk is mounted to the head and two torsion springs are respectively connected between the two pawl members and the operation disk.
The object of the present invention is to provide a ratchet wrench that employs two pawl members and each pawl member has two inclined surfaces connected by a straight surface. One of the two inclined surfaces and the straight surface of each pawl member is engaged with respective one of two parallel surfaces of the ridge member so as to provide a sufficient support when applying a large torque.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.


REFERENCES:
patent: 4347767 (1982-09-01), Gentiluomo
patent: 4807500 (1989-02-01), Main

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